In electric cars and hybrid cars, high-voltage power is stored in a capacitor disposed in a drive circuit to drive a motor at the time of operation and the power stored in the capacitor is discharged safely and rapidly by a rapid discharge circuit if a collision occurs. The rapid discharge circuit is formed of a discharge bypass circuit that is a circuit obtained by connecting a resistor and a switching element in series and is connected in parallel to the capacitor for example. At the time of a collision, the rapid discharge circuit can cause the discharge safely and rapidly by turning the switching element to the on-state to consume the power stored in the capacitor by the resistor. One form of the rapid discharge circuit is disclosed in Japanese patent laid-open publication No. 1996-33103 (“JP '103”).